Teaching Case

Premature boy with respiratory distress syndrom

This premature boy was born at 32 weeks gestation. Prematurity was due to fetal infection. He suffered of neonatal respiratory distress. A chest X-ray (fig. 1) was performed, showing confluent and irregular opacities in the left upper lobe. Hyaline membrane disease or pneumonia was suspected. On day 3, the patient presented faintness and some episodes of hypoxia which resolved with symptomatic treatment. A control chest radiograph on day 25 (fig. 2) showed an hyperlucency and hyperinflation of the left upper lobe with a shift of the mediastinum to the right side. A chest CT (fig. 3, 4, 5) examination was performed and showed giant lobar emphysema of the left lung without any bronchial obstruction. Endoscopic examination was normal. The patient underwent left superior lobectomy at the end of his first month of life because of a progressive aggravation of his respiratory status. Clinical and radiological follow-up were unremarkable.

Congenital lobar emphysema (CLE) is characterised by air trapping in a pulmonary lobe with secondary hyperinflation, compression, and atelectasis of adjacent lobe. Mediastinal shift is frequent. CLE is more common in boys, with a male/female ratio of 3/1. It becomes symptomatic within the first month of life in 50% of cases. Rarely the disease occurs after the age of 6 months. CLE is usually unilateral, occurring more frequently in the left upper lobe. The middle and right upper lobes are the other more frequent locations. Several lobes can simultaneously be involved. There are various causes of CLE though the etiology remains unknown in approximately 50% of cases. The most commonly identified cause of CLE is congenital cartilage deficiency (25% of cases). Congenital cartilage deficiency can comprise bronchomalacia, complete cartilage defect and bronchial stenosis. The remaining rare causes described in the literature are: secondary bronchial obstruction (mucous plug, epithelial hyperplasia caused by viral infections, external compression by abnormal vessels), iatrogenic (bronchial injury or stenosis after intubation), thoracic masses. Most patients present with polypnea and cyanosis during the neonatal period, with gradual distension. In other cases, mild respiratory distress can be observed in post natal period, with recurrent respiratory infections. A few patients with severe respiratory distress need urgent surgery. The diagnosis is usually confirmed on a plain chest X-ray as an hyperlucency of the affected side. The mediastinum is often shifted to the contra lateral side with herniation of the affected lobe and compression of contra lateral or ipsi lateral lobes. Widening of the rib spaces and flattening of the ipsi lateral diaphragm are seen when important distension is present. Chest CT is the best technique to evaluate the emphysema. In some instances and with MDCT, bronchial obstruction can be shown. Differential diagnosis includes pneumothorax, pulmonary cyst, atelectasia or lung hypoplasia. Bronchoscopy can be discussed in older children to rule out the diagnosis of foreign body. In a newborn, CLE can also be misdiagnosed as pneumonia or hyaline membrane disease. In this case, the consolidation of the left upper lobe at birth was the consequence of amniotic fluid trapping within the emphysema. Lobectomy is commonly the treatment in children with severe symptoms and in less than 2 months old infants. Treatment should be carried out in relative urgency in these conditions. Older children with mild to moderate respiratory symptoms require a conservative treatment with a close clinical and radiologic follow up. This disease needs close follow up in order to evaluate the consequences of the lobectomy as well as to detect multifocal involvement with a delayed presentation.